An inner compartment for medium voltage gas insulated switchgears includes: at least one inner compartment; and a housing. The inner compartment, or in case of several inner compartments, an inner of the inner compartment, or one of the inner compartments, is provided on an inner wall surface thereof at least partially with an insulating layer.

A method for loose joint detection in medium voltage switchgears with busbar joints, circuit breaker upper and lower spouts, and cable connection joints, arranged in an air insulated housing, and medium voltage switchgear itself, in order to create an effective loose joint detection with lower operating expense, but with high performance and accuracy, involves measuring actual temperatures at a first phase as a first temperature (T1), at a second phase as a second temperature (T2), at a third phase as a third temperature (T3), at predefined critical points, such as at the busbar joints, and/or at the circuit breaker upper spouts, and/or at the circuit breaker lower spouts, and/or the cable connection; and comparing temperatures in a logical dependency Ti>(Tj+dT), with ij, permuted with i from 1, 2, 3, and j from 1, 2, 3, and setting the alarm if the logical dependency is fulfilled.

A method for loose joint detection in medium voltage switchgears with busbar joints, circuit breaker upper and lower spouts, and cable connection joints, arranged in an air insulated housing, and medium voltage switchgear itself, in order to create an effective loose joint detection with lower operating expense, but with high performance and accuracy, involves measuring actual temperatures at a first phase as a first temperature (T1), at a second phase as a second temperature (T2), at a third phase as a third temperature (T3), at predefined critical points, such as at the busbar joints, and/or at the circuit breaker upper spouts, and/or at the circuit breaker lower spouts, and/or the cable connection; and comparing temperatures in a logical dependency Ti>(Tj+dT), with ij, permuted with i from 1, 2, 3, and j from 1, 2, 3, and setting the alarm if the logical dependency is fulfilled.

A circuit breaker includes an interrupter configured to selectively prevent a flow of electrical current through the circuit breaker, and an assembly. The assembly includes a housing, an interrupter mechanism, and an arc protection mechanism. The housing includes an opening configured to channel an arc fault discharge generated during an arc fault into the housing. The interrupter mechanism is coupled to the housing and the interrupter, and is configured to move the interrupter between a first position and a second position, wherein the first position prevents a flow of electrical current through the circuit breaker and the second position permits a flow of electrical current through the circuit breaker. The arc protection mechanism is within the housing and is configured to receive the arc fault discharge through the housing and to cause the interrupter to move to the first position in response to the arc fault discharge.

An insulating spacer and a gas insulation shutoff apparatus each having a high dielectric strength against adhesion of a metal foreign substance are provided without increasing size or complicating a shape of the insulating spacer. In an insulating spacer of a gas insulation shutoff apparatus including a grounded tank filled with an insulating gas, a high-voltage conductor provided within the grounded tank, and the insulating spacer supporting and fixing the high-voltage conductor within the grounded tank, the insulating spacer includes a conductor to be connected to the high-voltage conductor, an insulating structure supporting and fixing the conductor within the grounded tank, and a nonlinear resistance layer provided on a creepage surface of the insulating structure, and the nonlinear resistance layer is provided in a portion to be a high-field portion of the creepage surface of the insulating structure.

A gas insulated apparatus includes: a grounded metal tank in which an insulating gas is enclosed; a conductor disposed in the tank, voltage being applied to the conductor; and a non-linear resistance layer disposed on at least part of an inner surface of the tank and made from an insulating material containing a particle of a non-linear resistance material, the non-linear resistance material being conductive when voltage higher than or equal to a threshold is applied. The non-linear resistance layer has a thickness that is larger than a sum of a thickness of a conductive portion and a particle diameter of the non-linear resistance material, the conductive portion being a portion of the non-linear resistance layer that is conductive when voltage higher than or equal to the threshold is applied to a metal foreign object on the non-linear resistance layer.

A gas insulated apparatus includes: a grounded metal tank in which an insulating gas is enclosed; a conductor disposed in the tank, voltage being applied to the conductor; and a non-linear resistance layer disposed on at least part of an inner surface of the tank and made from an insulating material containing a particle of a non-linear resistance material, the non-linear resistance material being conductive when voltage higher than or equal to a threshold is applied. The non-linear resistance layer has a thickness that is larger than a sum of a thickness of a conductive portion and a particle diameter of the non-linear resistance material, the conductive portion being a portion of the non-linear resistance layer that is conductive when voltage higher than or equal to the threshold is applied to a metal foreign object on the non-linear resistance layer.

A switchgear device may include a frame defining an interior compartment, an electrical breaker component carried within the interior compartment, and a first optical sensor carried within the interior compartment. The switchgear device has a grounding device coupled to the electrical breaker component and being within the interior compartment. The grounding device includes a grounding switch switching between a first open state (i.e., ungrounded state) and a second closed state (i.e., grounded state), and an actuation device coupled to the grounding switch and configured to cause the grounding switch to switch between the first open state and the second closed state. The switchgear device includes a controller coupled to the electrical breaker component, the first optical sensor, and the grounding device and configured to cause the grounding switch to switch to the second closed state based upon the first optical sensor.

A switchboard monitoring system, according to one embodiment of the present specification, comprises: a thermal imaging apparatus for acquiring thermal imaging information of a device disposed in a switchboard panel; and a control apparatus for receiving the thermal imaging information from the thermal imaging apparatus, generating temperature information of the device on the basis of the received thermal imaging information, and detecting the temperature state of the device on the basis of the generated temperature information.

An arc quenching device includes a frame, at least one controlled-arcing device supported by the frame, and at least one contact assembly supported by the frame and electrically connected to the at least one controlled-arcing device. The device further includes a racking mechanism supported by the frame and including a motor and at least one actuator member driven by the motor and configured to engage a feature in an electrical equipment unit compartment to move the arc quenching device within the compartment and engage the at least one contact assembly with a bus of the electrical equipment unit. The arc quenching device may be configured to be installed in a cassette in the electrical equipment unit and the actuator member may be configured to engage a feature of the cassette.